<!-- <!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      .container {
        width: 600px;
        height: 600px;
        border: 1px solid;
        position: relative;
      }
      .box {
        width: 50px;
        height: 50px;
        background: red;
        position: absolute;
        left: 0px;
        top: 0px;
      }
      .box1 {
        width: 50px;
        height: 50px;
        background: green;
        position: absolute;
      }
    </style>
  </head>
  <body>
    <div class="container">
      <div class="box"></div>
      <div class="box1"></div>
    </div>
    <script>
      var containerEle = document.querySelector("container");
      var boxEle = document.querySelector(".box");
      var food = document.querySelector(".box1");
      var dir = "left";
      var speed = 4;
      document.onkeydown = function (e) {
        var key = e.key;
        if (key == "ArrowRight") {
          dir = "left";
          speed = Math.abs(speed);
        } else if (key == "ArrowDown") {
          dir = "top";
          speed = Math.abs(speed);
        } else if (key == "ArrowLeft") {
          dir = "left";
          speed = -Math.abs(speed);
        } else if (key == "ArrowUp") {
          dir = "top";
          speed = -Math.abs(speed);
        }
      };

      //  来一个绿色食物 ，红色碰到绿色之后 绿色食物消失
      var food = createfood();

      setInterval(function () {
        var leftNum = parseInt(getComputedStyle(boxEle)[dir]);
        boxEle.style[dir] = leftNum + speed + "px";
        if (
          Math.abs(food.offsetLeft - boxEle.offsetLeft) < boxEle.offsetWidth &&
          Math.abs(food.offsetTop - boxEle.offsetTop) < boxEle.offsetHeight
        ) {
          food.style.display = "none";
          food = createfood();
        }
      }, 50);
      function createfood() {
        food.style.left = randomNum(0, boxEle.clientWidth - 50) + "px";
        food.style.top = randomNum(0, boxEle.clientHeight - 50) + "px";
        return food;
      }

      function randomNum(min, max) {
        return parseInt(Math.random() * (max - min + 1)) + min;
      }

      // arrowfunction：箭头函数 ；
    </script>
  </body>
</html> -->
<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      .container {
        width: 600px;
        height: 600px;
        border: 1px solid;
        position: relative;
      }
      .box {
        width: 50px;
        height: 50px;
        background: red;
        position: absolute;
        left: 0px;
        top: 0px;
      }
    </style>
  </head>
  <body>
    <div class="container">
      <div class="box"></div>
    </div>
    <div class="score">分数:0</div>
    <script>
      var boxEle = document.querySelector(".box");
      var dir = "left";
      var speed = 4;
      document.onkeydown = function (e) {
        var key = e.key;
        if (key == "ArrowRight") {
          dir = "left";
          speed = Math.abs(speed);
        } else if (key == "ArrowDown") {
          dir = "top";
          speed = Math.abs(speed);
        } else if (key == "ArrowLeft") {
          dir = "left";
          speed = -Math.abs(speed);
        } else if (key == "ArrowUp") {
          dir = "top";
          speed = -Math.abs(speed);
        }
      };

      //  来一个绿色食物 ，红色碰到绿色之后 绿色食物消失
      var food = createFood();
      var num = 0;
      setInterval(function () {
        var leftNum = parseInt(getComputedStyle(boxEle)[dir]);
        boxEle.style[dir] = leftNum + speed + "px";

        // 检测碰撞
        // A 是 food 元素
        var AminX = food.offsetLeft;
        var AmaxX = AminX + food.offsetWidth;
        var AminY = food.offsetTop;
        var AmaxY = AminY + food.offsetHeight;

        // B 是 红色的方块  boxEle
        var BminX = boxEle.offsetLeft;
        var BmaxX = BminX + boxEle.offsetWidth;
        var BminY = boxEle.offsetTop;
        var BmaxY = BminY + boxEle.offsetHeight;

        if (AmaxX > BminX && AminX < BmaxX && AmaxY > BminY && AminY < BmaxY) {
          // console.log("碰了");
          food.remove();
          food = createFood();
          num++;
          document.querySelector(".score").innerHTML = "分数：" + num;
        }
      }, 50);

      // arrowfunction：箭头函数 ；
      function createFood() {
        var containerEle = document.querySelector(".container");
        var food = document.createElement("div");
        food.style.width = "50px";
        food.style.height = "50px";
        food.style.background = "blue";
        food.style.left = randomNum(0, containerEle.clientWidth - 50) + "px";
        food.style.top = randomNum(0, containerEle.clientHeight - 50) + "px";
        food.style.position = "absolute";
        containerEle.appendChild(food);
        return food;
      }

      function randomNum(min, max) {
        return parseInt(Math.random() * (max - min + 1)) + min;
      }
    </script>
  </body>
</html>
